well...not quite seamless.
i still receive a 'signature not valid' message on my late 2011 iMac at home. the only reason i was able to download it onto my late 2011 mbp was that i booted up in safe mode, accessed the apple store and purchased/downloaded—and, it took about 8 hours to download. quite franklin below apple's standards.
i attempted the same on my home machine, but it didn't work. all i get is the same 'signature not valid' message.